docs: def find_version(file_path):
      """
      Find the version of pygccxml.
  
      Used by setup.py and the sphinx's conf.py.
      Inspired by https://packaging.python.org/single_source_version/
  
      Args:
          file_path (str): path to the file containing the version.
      """
  
      with io.open(
              os.path.join(
                  os.path.dirname(__file__),
                  os.path.normpath(file_path)),
              encoding="utf8") as fp:
          content = fp.read()
  
      version_match = re.search(r"^__version__ = ['\"]([^'\"]*)['\"]",
                                content, re.M)
      if version_match:
          return version_match.group(1)
      raise RuntimeError("Unable to find version string.")